Air pressure mechanism



^` 3U, W R11.. PELTON ,59,88@

AIR PRESSURE MECHANISM Filed May 4, 1948 is la Inv? man lllIIIII-'I Patented May 30, 195() UNITED STATES PATENT OFFICE 9 Claims.

This invention relates to the removal of moisture from compressed air systems.

In the operation of compressed air systems of this type it is commonly found that water, oil and other foreign matter tends to collect in the bottom of the compressed air reservoir, particularly during the operation of the compressor pump. This accumulated liquid matter includes condensed moisture initially taken in with the air by the compressor as well as leakage of oil and the like in the system. Unlessit is removed from the reservoir, it tends to be transmitted throughout the remainder of the system and may seriously interfere with the operation thereof, as by freezing in cold weather or otherwise impeding proper operation. The present invention is concerned with maintaining such systems free and clear of this foreign matter and has special application to the problem as it arises in the operation of automotive buses, trolley cars, trucks and similar vehicles, as well as stationary installations, such as compressed air plants for shops, iilling stations and the like.

The invention has for its principal object the provision of a moisture ejecting device of improved and simple construction for use in conjunction with such compressed air systems which is economical to manufacture and easy to install, which will operate automatically and intermittently to discharge water and other undesired liquid materials which accumulate in the air reservoirs of such systems, and which will result in minimum loss of pressure in the system both during the discharge operation and by leakage therethrough at other times while in use.

Other objects and advantages of the invention will be apparent from the following description, the accompanying drawing and the appended claims.

In the drawing:

Fig. l is a diagrammatic view illustrating parts of a compressed air system incorporating a drainage device in accordance With the invention;

Fig. 2 is an enlarged section on the line 2-2 of Fig. l illustrating the construction of the drainage device;

Figs. 3 and 4 are views similar to Fig. 2 showing the movable parts of the device in diiierent positions to illustrate its operation;

Fig. 5 shows the device as viewed from the top in Fig. l; and

Figs. 6 and 7 are detail views in section on the lines G--B and 7 1, respectively, of Fig. 4.

Referring to the drawing, which illustrates a preferred embodiment of the invention, the compressor indicated generally at I0 operates to supply air under pressure through pipe II to reser- Voir tank I2, and a pipe I4 leads from the bottom of tank I2 to the moisture ejecting device indicated generally at l5, this valve being shown as provided with a drain pipe I6. A pipe I8 leads from tank I2 to mechanism such as the doors and brakes of a bus operated by air pressure from tank I2, and a pipe 20 leads from tank I2 to a governor 22, which is in turn connected through T-joint 24 and pipes 25 and 26 back to compressor I0 and to the top of valve device I5, respectively.

With the exception of the moisture ejecting device I5, the parts of this system are conventional and Well-known, the governor operating to maintain the pressure within tank I2 Within a predetermined range by controlling the action of compressor I0. This operation is such that when the pressure in tank I2 is within the desired range, full line pressure is applied in pipes 25 and 25, but when the pressure in the tank falls below the desired level, the compressor supplies air under pressure through pipe li to the tank until the pressure within the tank has again been built up to the desired level. During this latter operation, line pressure is cut off from pipes 25 and 26, and it will thus be seen that the governor operates intermittently to supply and cut ofi line pressure in pipe 26 and hence in the device I5.

The construction and operation of the moisture ejecting device I5 are shown in enlarged detail in Figs. 2 to 7. A generally cylindrical. casing 30 forms the main body of the device and is provided at opposite sides with apertured ears EI which receive mounting bolts 32 for installing the device at a desired location. The interior of casing 30 includes an integral annular partition 33' having a cylindrical central bore 34, and a cap 35 is threaded on the lower end of the casing and cooperates With partition 33 to denne a chamber 3S which serves as the discharge chamber in the operation of the device. The outer end of cap 35 is tapped for a threaded connection with the discharge pipe I6.

A plunger 40 is mounted for reciprocating movement in the bore 34 and carries at its upper end a piston 44 provided with a peripheral groove for receiving a rubber O-ring 45 providing a fluidtight seal against the inner wall of the casing. This piston thus has the eiect of separating the interior of the casing above partition 33 into an inner chamber 50 and outer chamber 5I. The chamber 50 serves as the inlet chamber and is provided with a tapped boss 52 for receiving the connecting pipe I4 from tank I2. The chamber 5I serves as the pressure chamber, the outer end thereof being closed by a cap 55 having a tapped outer portion for receiving the pipe 2S. It will also be noted that the portion 5S of the cap is connected with the interior of chamber 5l by a restricted orifice 5*! to retard the passage of pressure air between pipe 2@ and chamber 5i, a diameter of approximately .055 inch having been found satisfactory for this orifice 5l.

rlhe cylindrical upperportion 59 of plunger lll is of considerable diameter, greater than that of the central bore 33, and thus provides a substantially greater effective pressure area at the outer end of piston is exposed to the pressure through pipe 26 than the annular area of the piston exposed to the pressure from pipe ifi. The lower end of the plunger portion 59 is tapered at E@ to form a valve adapted to seat in and close the chamfered upper end of bore The plunger talso includes a cylindrical portion tl adjacent its lower end which is of such diameter as to have sliding t in bore 3d, but the plunger has flats 62 formed thereon intermediate the portions @il and ti! which provide passageways through bore 3'4 when neither of the portions @il or 6i is in seated relation with bore 353, as indicated at t3 in Fig. 3. The arcuate portions @d of the plunger between the flats 52 cooperate with the bore Se to maintain the plunger properly aligned in the casing.

A valve member 65 is secured to the lower end of plunger 5.3 a'nd is provided with a tapered portion 65 similar to the portion 60 and similarly adapted to seat in and close the chamfered lower end of bore Valve 65 is received on the cylindrical end portion 6'1 of the plunger of smaller diameter than the portion 6 l, and these parts are held together by a bolt 68 which traverses the plunger and is provided with a suitable lock nut E9. The valve portions Gil and 66 thus serve alternately to seat in and close the opposite ends of bore 3a and cooperate with the partition 33 to limit the reciprocating movement of the plunger, but it will be noted that these valves are spaced by a distance substantially greater than the axial length of bore 34 so that both can not be in seated position at the same time.

A flexible rubber piston member '.'G is also secured to plunger Ml within discharge chamber 35, this piston member being provided with a metal insert 7i and being mounted on bolt 68 betweenfthe outer end of valve member 65 and a metal washer 'F2 for added stillness. This piston l!) cooperates with the inner wall of the discharge chamber 36 to supplement the action of valve surfaces 6G and 66 in alternately opening andV closing communication between inlet chamber 36 and outlet I6.

The inner wall of chamber 36 includes axially spaced portions 'l5 and 76 of cylindrical crosssection separated by oppositely flared frusto-conical portions Tl and E8 of substantially greater total axial length than the corresponding dimension of piston 18. The circumferential surface of piston 'm includes a narrow cylindrical land 80` of greater diameter than the wall portions 'l5 and 'i6 for close sealing iit therewith, satisfactory results having been obtained with this land approximately .020 to .030 inch greater in diameter than the wall portions 'l5 and '16. The remainder Si of the circumferential surface of piston 1B is tapered from a maximum diameter at the land BQ to a minimum diameter less than that of the wall portions and 16, for example a diameter of 15/16 inch as opposed to a diameter of 1 inch for these wall portions.

lt will thus be seen that when plunger t0 is at either of its limit positions shown in Figs. 2 and 4, the piston l@ will be compressed within one of the wall portions '5 or 'I6 and will thus act as a valve to seal the upper part of discharge chamber 35 from outlet l, but when the plunger 4t is an intermediate position wherein piston 'l0 is opposite the wall portions 'Vl and 18, as shown in Fig. 3, there is an annular clearance or passageway between the piston and the walls of `chamber 36 as indicated at 82. This clearance provides for discharge from the device through the passageways 63 and 82 of foreign matter accumulating in chamber 5!) when the plunger 40 is in motion between the relative positions shown in Figs. 2 and 4, and satisfactory results have been obtained with the dimensions of the respective parts such that the average width of this clearance is of the order of .025 inch. Also, the boundary between each of the ared portions 'l1 and 'E8 andthe adjacent cylindrical wall portion is rounded about a small radius to facilitate movement of piston lli within chamber 36.

In operation, the pipe I4 provides for constant drainage from the reservoir tank l2 to the inlet chamber 5G, and also the pressure supplied from the reservoir tank to chamber 5U is effective against the inner surface of piston l to urge the plunger it to the position shown in Fig. 2, wherein the valve surface 68 seats against the lower end of bore 34 and the piston 10 seals within the wall portion l5 to supplement the sealing action of the valve. A coil spring 35 is shown as positioned in chamber 5) between piston 44 and partition 33, such a spring of tension substantially balancingl the weight of plunger 40 having been found useful to impart general smoothness t0 the operation of the device.

The governor 22 provides for intermittent'application of line pressure through pipe 26 to the pressure chamber 5I to eiect intermittent reciprocation of plunger 4l! andaccompanying discharge of water and' any other foreign materials vdraining from the reservoir tank. When the line pressure is applied in chamber 5I it will overcome the combined pressure of spring' 85 and the tank pressure in chamber 50, as a result of the greater effective area of piston 44 'in chamber 5 I, and will thus urge the plunger downwardly as viewed in the drawing until the valve surface 60 seats on the upper end of bore 34. The plunger will thus move from thek position shown in Fig. 2 through the position shown in Fig. 3 until it reaches the position shown in Fig. 4, this movement being retarded as a result of the restriction on the entering pressure air through the orifice 51.

In the intermediate position shown in Fig. 3, there will be direct communication frominlet chamber 5S to the upper end of discharge chamber 38 through the passages 63 provided by the flats t2 on the plunger, and'at the same time there will be an annular passageway around piston lil as a result of the clearance at 82 between this piston and the wall portions T13 and V'(8. Therefore, the tank pressure will be applied directlythrough chamber 50 to the outlet pipe I6, thus effectively blowing out in a spurt any foreign materials which drained into the chamber EQ while the plunger was in the position shown in Fig.r 2.

The parts remain in the relative positions shown in Fig. e until the pressure in reservoir tank i2 again falls below the desired minimum level, and when this occurs the governor will out off the line pressure effective upon pipe 26. Since the tank pressure is continually applied inchamber 50, the plungerwill then be caused to reverse its previous motion andffreturn tothe position showny in Fig. 2. Thus it will again pass through intermediate` position shown in Fig. 3, and at such timethere will be another spurt of .discharged foreign material through the passage- Ways 63 and 82 and out throughpipe I6;

This intermediate reciprocation of` the. plunger will` continue so. long as the air system is operating and the pressure in tank l2 fluctuates, which happens relatively rapidly during the operation of trolleys, buses and similar conveyances in which compressed air systems of the typeshown in Fig. 1 are commonlylemployecl. The device,` therefore, will operate intermittently whenever the governor 22 functions to effect automatic discharge os the water and` other foreign materials draining fromV the reservoir tank. The device is also simple to install, since it requires only the two `connections to the inlet and pressure chambers 50 and 5I. Furthermore, it can be installed at any convenient location in the vehicle and does not have to be positioned below the level of the bottom of tank I2, the device having been found to operate with full effectiveness even when mounted above the reservoir tank in such position that drainage is against the force of gravity and isA efectediby the intermittent passage of air through the drainage pipe I4 when the device is in open orV dischargeV position. In addition, the device is Wellsuited for use in conjunction `with stationary compressed air systems, such as are commonly employed in shops, lling stations and the like, as Well as with similar systems utilizing compressed gasesV other than air and wherein liquid mayaccumulate.

It should,` also be noted that the` device can be operated equally well when installed in a vehicle by connecting the` pipe 26 to other circuits of the compressed airV system such as the door operating circuit of a bus.` In such installations, pressure is applied in pressurechamber 5i whenever air pressure is` suppliedA to the doors or brakes foroperatingpurposes, `and the pressure is released when the doors are closed or the brakesA released.. With any oi these arrange,- ments, the loss ofair pressure throughthe drain,- age device` is very slight since thef connection be,- tween the tank and the :atmosphere is open for only the instant whenthe plunger is passing between its two limit positionsand also the open areas through the bore 34 andaround the piston 'lil are of relatively small cross-sectional area. Thus the draining operation produces little clecrease in the pressure within the reservoir, which is highly advantageous particularly with reservoirs of `relatively small capacity such as are commonly used in compressed air systems for vehicles Accordingly the use of the device does not materially add to the load on the compressor, and its effective elimination oi undesired foreign materials from the system adds greatly to the eiiiciencyof the system as a whole.

This application is a continuation in part of my application Serial No. 631,275 led` November 28,1945.

While` the apparatus herein described constitutes a preferredembodiment of the invention, it is to` be understood that the invention is not limited to this precise apparatus, and that changes may be made therein without departing from the scope of the invention which is delned in the appended claims.

What is claimed is:

1. A moisture ejecting devicefor use in a compressed `air system including.` an air reservoir comprising a casing, an annular partition in said casing denning therein an inletV chamber and a discharge chamber, said partitionhaving a central bore providing communication between said chambers, said discharge chamberf having anoutlet to the atmosphere, a plunger mounted for sliding movement in said borerand extending into both said chambers,` said plunger having valve portions at either end thereof adapted to seat against and close the opposite'ends of saidbore, said valves being spaced on said plunger by a distance greater than the axial length of said bore to pre'vent'both said valves from seating at the same time,` means forconnecting` said inletchamber to said reservoir to provide for continuous drainagelfrom said rreservoir to said inlet chamber, means` responsive to the pressure` within said inlet chamber` for urging `saidplunger` in a direction to cause the valve thereon in said discharge chamber toclose said bore and to cause the valve thereon in said inlet chamber to open said bore, and means for moving said plunger against the action ofi said pressure responsive means in a direction to cause` the `valve thereon in said inlet chamber to close said bore and to cause the valve thereon in` saiddischarge chamu ber to close said bore, said plunger having por tions thereof cut away intermediatesaid valves to provide a passageway through said bore when neither of said valves` is seated for effecting direct communication from said inlet chamber to said outlet.

2. A moisture ejectingdevice for use in. acompressed air system including` an air reservoir, comprising a casing` having` an annular partition dening therein an inlet chamber and a di charge chamber, said partition having a central bore connecting said chambers, said discharge chamber having an. outlet to the atmosphere, an elongated plunger mounted for sliding movement in said bore, and havingV axially spaced valve portions adapted to seat on said partition to close saidk bore, said valves being spaced by a distance greater than the axial length of said bore to prevent both said valves from seating at the same time, a flexible pistonmember secured to said plunger within said discharge chamber, said discharge chamber including axially spaced inner wall portions of such` dimensions as to receive said piston in sealing engagement therewith when either of said valves is seated,` a portion of said inner Wall intermediate said spaced Wall portions being of greater diameter than said piston to provide: passageway Within said discharge chamber around said'piston when said plunger is in such position that neither of said valves is seated, meansv for connectingsaid inlet chamber to said reservoir to provideV for` continuous drainage from said reservoir to said inlet chamber, means responsive to the pressure within said inlet chamber for 'urging said plunger in a direction to cause one: of said'valves to close said bore, and means for moving saidt plunger against the action of said pressure responsive means in a direction to cause the other of said valves to close said bore, said plunger having portions thereof cut away intermediate said valves to provide continuous passageway through said bore and around' said piston when neither of saidl valves is seated for direct communication from said inlet chamber to said outlet.

3. A moisture electing` device forusein .a compressed air system including an air reservoir, comprising a casing, an annular partition in said casing defining therein an inlet chamber and a discharge chamber, said partition having a central .bore connecting said chambers, said discharge chamber having an outlet to the atmosphere, a, plunger mounted for sliding movement in said bore, means establishing limit positions for said movement of said plunger, a flexible piston member secured to said plunger within said discharge chamber, said discharge chamber including axially spaced inner wall portions of such dimensions as to receive said piston in sealing engagement therewith when said plunger is in either of said limit positions, means for connecting said inlet chamber to said reservoir to provide for continuous drainage from said reservoir to said inlet chamber, means responsive to the pressure within said inlet chamber for urging said plunger to one of said limit positions, and means for moving said plunger against the action of said pressure responsive means to the other said limit position, a portion of said inner wall of said discharge chamber intermediate said spaced wall portions thereof being of greater diameter than said piston to provide passageway within said discharge chamber around said piston when said plunger is intermediate said limit positions for eiiecting direct communication from said inlet chamber to said outlet.

4. A moisture ejecting device for use in a compressed air system including an air reservoir, comprising a casing, an annular partition in said casing defining therein an inlet chamber and a discharge chamber, said partition having a central bore connecting said chambers, said discharge chamber having an outlet to the atmosphere, a plunger mounted for sliding movement in said bore, means establishing limit positions for said movement of said plunger, a exible piston member secured to said plunger within said discharge chamber, said discharge chamber including axially spaced cylindrical inner wall portions, the peripheral surface of said piston including a cylindrical portion of greater diameter than said cylindrical wall portions and a portion tapering from said cylindrical portion to a, diameter less than said cylindrical wall portion, means for connecting said inlet chamber to said reservoir to provide for continuous drainage from said reservoir to said inlet ber, means responsive to the pressure within said inlet chamber for urging said plunger to one oi said limit positions, and means for moving said plunger against the action of said pressure responsive means to the other said limit position, said inner wall oi said discharge chamber intermediate said cylindrical portions being flared outwardly from each of said cylindrical portions to a diameter greater than said cylindrical portion of said piston, said flared wall portions being of substantially greater axial length than said piston to provide passageway within said discharge chamber around said piston when said plunger is intermediate said limit positions to eiect direct communication from said inlet chamber to said outlet.

5. A moisture eiecting device for use in a com pressed air system including an air reservoir, comprising a casing having an annular partition separating the interior thereof into a discharge chamber and another chamber, said discharge chamber having an outlet, said partition having a central bore connecting said chambers, a plunger mounted for sliding movement in said bore and extending into both'said chambers, a piston carried by said plunger in said other chamber to separate said other chamber into an inlet chamber adjacent said partition and a pressure chamber with said piston presenting greater eiiective pressure area in said pressure chamber than in said inlet chamber, said plunger having axially spaced valve portions adapted to seat on said partition to close said bore, said valves being spaced by a distance greater than the axial length of said bore to prevent both said valves from seatingat the same time, means for connecting said inlet chamber to said reservoir to provide for continuous application of pressure from said reservoir to said piston in said inlet chamber to urge said plunger in a direction to cause one of said valves to close said bore, and means for connecting said pressure chamber to said system to apply line pressure intermittently in said pressure chamber for moving said plunger in a direction to cause the other said valve to close said bore, said plunger having portions thereof cut away intermediate said valves to provide a passageway through said bore when neither of' said Valves is seated to eiiect direct communication from said inlet chamber to said outlet.

6. A moisture ejecting device for use in a compressed air system including an air reservoir, comprising a casing having an annular partition defining therein a discharge chamber and another chamber, said discharge chamber having an outlet, said partition having a central bore connecting said chambers, a plunger reciprocable in said bore and extending into both said chambers, a piston carried by said plunger and separating said other chamber into an inlet chamber adjacent said partition and a pressure chamber with said piston presenting greater eiiective pressure area in said pressure chamber than in said inlet chamber, said plunger including axially spaced Valve portions adapted to close said bore and spaced sufficiently to prevent both said valves from being in :bore-closing position at the same time, `a flexible piston secured to said plunger within said discharge chamber for sealing engagement with the walls of said chamber when either of said valves is in bore-closing pcsition, said wall including a, portion of greater diameter than said flexible piston to provide passageway around said flexible piston when said plunger is in such position that neither of said valves is in bore-closing position, means for connecting said inlet chamber to said reservoir to provide continuous pressure from said reservoir in said inlet chamber to urge said plunger in a direction to cause one of said valves to close said bore, and means for connecting said pressure chamber to said system to apply line pressure intermittently in said pressure chamber for moving said plunger in the opposite direction, said plunger having portions thereof cut away intermediate said Valves to provide continuous passageway through said bore and around said flexible piston when neither of said valves is in bore-closing position.

'.7. A moisture ejecting device for use in a compressed air system including an air reservoir, comprising a casing having an annular partition separating the interior thereof into a discharge chamber and another chamber, said discharge chamber having an outlet, said partition having a. central bore connecting said chambers, a plunger reciprocable in said bore and extending into both said chambers, a piston carried by said plunger 9 in said other chamber to separate said other chamber into an inlet chamber adjacent said partition and a pressure chamber with said piston presenting greater elective pressLu-e area in said pressure chamber than in said inlet chamber, means establishing limit positions for said movement of said plunger, a iieXible piston member secured to said plunger within said discharge chamber, said discharge chamber including axially spaced inner wall portions o1 such dimensions as to receive said flexible piston in sealing engagement therewith when said plunger is in either of said limit positions, means for connecting said inlet chamber to said reservoir to provide for continuous pressure in said inlet chamber urging said plunger to one of said limit positions, and means for connecting said pressure chamber to said system to apply line pressure intermittently in said pressure chamber for moving said plunger to the other said limit L position, a portion of said inner wall of said discharge chamber intermediate said spaced portions being of greater diameter than said flexible piston to provide passageway around said flexible piston when said plunger is intermediate said limit positions,

8. A moisture ejecting device for use in a compressed air system including an air reservoir, comprising a casing, an annular partition in said casing dening therein an inlet chamber and a discharge chamber, said partition having a central bore connecting said chambers, said discharge chamber having an outlet to the atmosphere, a plunger mounted for sliding movement in said bore and extending into both said chambers, valve means on said plunger adapted to seat on the ends of said bore to establish limit positions for said movement of said plunger and to close communication between said inlet chamber and said outlet when said plunger is in either of said limit positions, means for connecting said inlet chamber to said reservoir to provide for continuous drainage of foreign material from said reservoir to said inlet chamber, means responsive to pressure within said inlet chamber for urging said plunger to one of said limit positions, means for intermittently moving said plunger against the action of said pressure responsive means to the other said limit position, means cooperating with said valve means to provide direct communication from said inlet chamber to said outlet when said plunger is intermediate said limit positions, and means for retarding the movement of said plunger in each direction to provide intervals of appreciable duration of said direct communication to assure effective discharge from said inlet chamber of moisture accumulated therein.

9. A moisture ejecting device for use in a compressed air system including an air reservoir, comprising a casing, an annular partition in said casing defining therein an inlet chamber and a discharge chamber, said partition having a central bore connecting said chambers, said discharge chamber having an outlet to the atmosphere, a plunger mounted for sliding movement in said bore and extending into both said chambers, valve means on said plunger adapted to seat on the ends of said bore to establish limit positions for said movement of said plunger and to close communication between said inlet chamber and said outlet when said plunger is in either of said limit positions, means for connecting said inlet chamber to said reservoir to provide for oontinuous drainage of foreign material from said reservoir to said inlet chamber, means :responsive to pressure within said inlet chamber for urging said plunger to one of said limit positions, a piston carried by said plunger of greater eiective area than said pressure responsive means cooperating with said casing to form a pressure chamber, means for intermittently connecting said pressure chamber to said system to said piston to move said plunger against the action of said pressure responsive means to the other said limit position, means cooperating with said valve means to provide direct communication from said inlet chamber to said outlet when said plunger is intermediate said limit positions, and means for restricting the connection between said pressure chamber and said system to retard the movement of said plunger between said limit positions to provide intermittent intervals oi appreciable duration when said inlet chamber is in direct communication with said outlet for assuring effective discharge of moisture accumulated therein.

ROBERT L. PELTON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,680,288 Gottschalk Aug. 14, 1928 2,328,649 Jerome Sept. 7, 1943 2,410,799 Bassett l- Nov. l2, 1946 2,418,440 White et al Apr. 1, 19a? 

